This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.
The promptness of response to a user request is a key indicator of the quality of a packet data service. Operators regularly collect measurements of response time at various network elements to be able to monitor and improve end-user experience.
This invention makes it possible to use measurements collected at link layer (layer 2) to improve the user experience of a packet data application on the network layer (layer 3).
End-user applications use packets carried at layer 3 and above in the Open Systems Interconnection (OSI) model.
To measure the response time accurately, it is essential to collect measurements as close to the user as possible.
The collected measurement must contain sufficient data to identify the request and the response, and to accurately determine the time each was sent and received. The message length must also be known, which requires that the entire packet be captured.
When the correct set of packets and their time stamps are known, the greatest component of the indicator is identified, making it possible to localize and eliminate any source of unnecessary delays in the transaction path, thus improving the application design to consistently deliver better user experience.
The backbone of the network is usually connected together with a high-speed and a low-delay connection technology, where performance is tightly controlled by the operator, with plenty of throughput to carry the offered load with minimum delay.
The remaining parts of the end-to-end service delivery path consist of the “edge”, comprising the access and user terminal, which share limited resources with other users. When limited resources are shared, delay is incurred in accessing the resource.
Battery saving techniques add to the delay. When access connection is established, the resulting throughput depends on factors such as the type of access technology, channel, quality, and throughput of service negotiated. Because of the range of possible outcomes, the access and terminal incur a relatively large and variable delay compared to the other segments of the path. This contribution must therefore be measured accurately to correctly quantify its share in the end-to-end delay experienced by the user.
A well-known method exists to capture the time stamp, header, and packet data carried on certain network access hardware, such as Ethernet. This method is known as Packet Capture, tcpdump, or PCAP method.
The PCAP method works natively on a wide range of fixed and wireless access hardware, including WiFi, ATM, and IRDA. PCAP is used to collect measurements in the backbone network.
In access nodes, such as base station controller (BSC) and Radio Network Controller (RNC), frame time stamp and data can be captured at layer 2.
Layer 3 packet capture using PCAP is possible in a mobile packet core or backbone node, which works well for packet data application measurements.
A mobile radio access network controller works at layer 2, with frames belonging to the Radio Link Control (RLC) protocol. A frame is captured with its timestamp at layer 2, but the corresponding layer-3 information is not readily available at layer 2 with adequate precision and completeness.
To be able to use the measurement data collected on layer 2, the RLC protocol frames on layer 2 must be reassembled to constitute layer 3 IP packets. This reassembly procedure can be time consuming and prone to error if attempted manually. The magnitude of the challenge and potential for error is multiplied with the number of packets that must be handled to achieve a level of significance of measurement, making manual/mental processing prohibitively costly.